cuego: use Runtime to simplify code

This helps implementing the Go encoder
down the line.

Change-Id: I3497af993f108085fe438a2c56eb61c08e887f8e
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2701
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: mpvl

cue/go.go

@@ -37,24 +37,24 @@ import (
 // optimized.
 
 func init() {
-	internal.FromGoValue = func(instance, x interface{}) interface{} {
-		return convertValue(instance.(*Instance), x)
+	internal.FromGoValue = func(runtime, x interface{}) interface{} {
+		return convertValue(runtime.(*Runtime), x)
 	}
 
-	internal.FromGoType = func(instance, x interface{}) interface{} {
-		return convertType(instance.(*Instance), x)
+	internal.FromGoType = func(runtime, x interface{}) interface{} {
+		return convertType(runtime.(*Runtime), x)
 	}
 }
 
-func convertValue(inst *Instance, x interface{}) Value {
-	ctx := inst.index.newContext()
+func convertValue(r *Runtime, x interface{}) Value {
+	ctx := r.index().newContext()
 	v := convert(ctx, baseValue{}, x)
 	return newValueRoot(ctx, v)
 }
 
-func convertType(inst *Instance, x interface{}) Value {
-	ctx := inst.index.newContext()
-	v := convertGoType(inst, reflect.TypeOf(x))
+func convertType(r *Runtime, x interface{}) Value {
+	ctx := r.index().newContext()
+	v := convertGoType(r, reflect.TypeOf(x))
 	return newValueRoot(ctx, v)
 
 }
@@ -386,8 +386,8 @@ var (
 	mutex     sync.Mutex
 )
 
-func convertGoType(inst *Instance, t reflect.Type) value {
-	ctx := inst.newContext()
+func convertGoType(r *Runtime, t reflect.Type) value {
+	ctx := r.index().newContext()
 	// TODO: this can be much more efficient.
 	mutex.Lock()
 	defer mutex.Unlock()

cuego/cuego.go

@@ -20,7 +20,6 @@ import (
 	"sync"
 
 	"cuelang.org/go/cue"
-	"cuelang.org/go/cue/build"
 	"cuelang.org/go/cue/parser"
 	"cuelang.org/go/internal"
 )
@@ -160,16 +159,13 @@ func (c *Context) Constrain(x interface{}, constraints string) error {
 var (
 	mutex    sync.Mutex
 	instance *cue.Instance
+	runtime  = &cue.Runtime{}
 )
 
 func init() {
-	context := build.NewContext()
-	inst := context.NewInstance("<cuego>", nil)
-	if err := inst.AddFile("<cuego>", "{}"); err != nil {
-		panic(err)
-	}
-	instance = cue.Build([]*build.Instance{inst})[0]
-	if err := instance.Err; err != nil {
+	var err error
+	instance, err = runtime.Compile("<cuego>", "{}")
+	if err != nil {
 		panic(err)
 	}
 }
@@ -180,7 +176,7 @@ func fromGoValue(x interface{}) (v cue.Value, err error) {
 	// Instance) here as any previously unrecognized field can never match an
 	// existing one and can only be merged.
 	mutex.Lock()
-	v = internal.FromGoValue(instance, x).(cue.Value)
+	v = internal.FromGoValue(runtime, x).(cue.Value)
 	mutex.Unlock()
 	return v, nil
 
@@ -205,7 +201,7 @@ func fromGoType(x interface{}) cue.Value {
 	// Instance) here as any previously unrecognized field can never match an
 	// existing one and can only be merged.
 	mutex.Lock()
-	v := internal.FromGoType(instance, x).(cue.Value)
+	v := internal.FromGoType(runtime, x).(cue.Value)
 	mutex.Unlock()
 	return v
 }